From patchwork Mon Feb 3 12:57:14 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Marc-Andr=C3=A9_Lureau?= X-Patchwork-Id: 13957434 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EA35DC02192 for ; Mon, 3 Feb 2025 12:58:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tew1Q-00063F-Ke; Mon, 03 Feb 2025 07:57:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tew1P-00062q-1K for qemu-devel@nongnu.org; Mon, 03 Feb 2025 07:57:51 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tew1M-0006n5-Dk for qemu-devel@nongnu.org; Mon, 03 Feb 2025 07:57:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738587465; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pFBlPoR8oobvBzAsrZH9vZK9ovsNpf2glQXgbzvjxyg=; b=R5cAmrd55vY0MlAZ9/ITRl78wx48IOaoXD8zyWKoWvM3TXUTg0jcUy4T/e5wZZ+SFJa8h8 FxS0G81ISHDDZs+qdh7vskKkbhQPGS2MFL2metpp4WlEhYqJX0vafsMJRC5+DmlmuWgBkY SVgGTbTSq2RHtsH/YZdRIE6jbPTz8tQ= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-122-GvSuylU_OXStypIeigujIQ-1; Mon, 03 Feb 2025 07:57:42 -0500 X-MC-Unique: GvSuylU_OXStypIeigujIQ-1 X-Mimecast-MFC-AGG-ID: GvSuylU_OXStypIeigujIQ Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A0C3919560BA; Mon, 3 Feb 2025 12:57:39 +0000 (UTC) Received: from localhost (unknown [10.39.208.25]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 5BAA5195608E; Mon, 3 Feb 2025 12:57:36 +0000 (UTC) From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Cc: Eric Blake , Paolo Bonzini , Mahmoud Mandour , Markus Armbruster , peter.maydell@linaro.org, Gerd Hoffmann , Alexandre Iooss , =?utf-8?q?Alex_Benn=C3=A9e?= , Pierrick Bouvier , =?utf-8?q?Marc-Andr=C3=A9_L?= =?utf-8?q?ureau?= , Roman Penyaev Subject: [PULL 2/8] chardev/char-hub: implement backend chardev aggregator Date: Mon, 3 Feb 2025 16:57:14 +0400 Message-ID: <20250203125721.640451-3-marcandre.lureau@redhat.com> In-Reply-To: <20250203125721.640451-1-marcandre.lureau@redhat.com> References: <20250203125721.640451-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.133.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Roman Penyaev This patch implements a new chardev backend `hub` device, which aggregates input from multiple backend devices and forwards it to a single frontend device. Additionally, `hub` device takes the output from the frontend device and sends it back to all the connected backend devices. This allows for seamless interaction between different backend devices and a single frontend interface. The idea of the change is trivial: keep list of backend devices (up to 4), init them on demand and forward data buffer back and forth. The following is QEMU command line example: -chardev pty,path=/tmp/pty,id=pty0 \ -chardev vc,id=vc0 \ -chardev hub,id=hub0,chardevs.0=pty0,chardevs.1=vc0 \ -device virtconsole,chardev=hub0 \ -vnc 0.0.0.0:0 Which creates 2 backend devices: text virtual console (`vc0`) and a pseudo TTY (`pty0`) connected to the single virtio hvc console with the backend aggregator (`hub0`) help. `vc0` renders text to an image, which can be shared over the VNC protocol. `pty0` is a pseudo TTY backend which provides biderectional communication to the virtio hvc console. 'chardevs.N' list syntax is used for the sake of compatibility with the representation of JSON lists in 'key=val' pairs format of the util/keyval.c, despite the fact that modern QAPI way of parsing, namely qobject_input_visitor_new_str(), is not used. Choice of keeping QAPI list syntax may help to smoothly switch to modern parsing in the future. Signed-off-by: Roman Penyaev Reviewed-by: "Marc-André Lureau" Cc: qemu-devel@nongnu.org Message-ID: <20250123085327.965501-3-r.peniaev@gmail.com> --- qapi/char.json | 27 ++++ chardev/chardev-internal.h | 51 ++++++- include/chardev/char.h | 1 + chardev/char-hub.c | 301 +++++++++++++++++++++++++++++++++++++ chardev/char.c | 23 ++- chardev/meson.build | 1 + 6 files changed, 401 insertions(+), 3 deletions(-) create mode 100644 chardev/char-hub.c diff --git a/qapi/char.json b/qapi/char.json index e045354350..f02b66c06b 100644 --- a/qapi/char.json +++ b/qapi/char.json @@ -332,6 +332,19 @@ 'data': { 'chardev': 'str' }, 'base': 'ChardevCommon' } +## +# @ChardevHub: +# +# Configuration info for hub chardevs. +# +# @chardevs: List of chardev IDs, which should be added to this hub +# +# Since: 10.0 +## +{ 'struct': 'ChardevHub', + 'data': { 'chardevs': ['str'] }, + 'base': 'ChardevCommon' } + ## # @ChardevStdio: # @@ -479,6 +492,8 @@ # # @mux: (since 1.5) # +# @hub: (since 10.0) +# # @msmouse: emulated Microsoft serial mouse (since 1.5) # # @wctablet: emulated Wacom Penpartner serial tablet (since 2.9) @@ -521,6 +536,7 @@ 'pty', 'null', 'mux', + 'hub', 'msmouse', 'wctablet', { 'name': 'braille', 'if': 'CONFIG_BRLAPI' }, @@ -595,6 +611,16 @@ { 'struct': 'ChardevMuxWrapper', 'data': { 'data': 'ChardevMux' } } +## +# @ChardevHubWrapper: +# +# @data: Configuration info for hub chardevs +# +# Since: 10.0 +## +{ 'struct': 'ChardevHubWrapper', + 'data': { 'data': 'ChardevHub' } } + ## # @ChardevStdioWrapper: # @@ -703,6 +729,7 @@ 'pty': 'ChardevPtyWrapper', 'null': 'ChardevCommonWrapper', 'mux': 'ChardevMuxWrapper', + 'hub': 'ChardevHubWrapper', 'msmouse': 'ChardevCommonWrapper', 'wctablet': 'ChardevCommonWrapper', 'braille': { 'type': 'ChardevCommonWrapper', diff --git a/chardev/chardev-internal.h b/chardev/chardev-internal.h index 853807f3cb..9752dd75f7 100644 --- a/chardev/chardev-internal.h +++ b/chardev/chardev-internal.h @@ -29,13 +29,16 @@ #include "chardev/char-fe.h" #include "qom/object.h" +#define MAX_HUB 4 #define MAX_MUX 4 #define MUX_BUFFER_SIZE 32 /* Must be a power of 2. */ #define MUX_BUFFER_MASK (MUX_BUFFER_SIZE - 1) struct MuxChardev { Chardev parent; + /* Linked frontends */ CharBackend *backends[MAX_MUX]; + /* Linked backend */ CharBackend chr; unsigned long mux_bitset; int focus; @@ -53,11 +56,57 @@ struct MuxChardev { int64_t timestamps_start; }; typedef struct MuxChardev MuxChardev; +typedef struct HubChardev HubChardev; +typedef struct HubCharBackend HubCharBackend; + +/* + * Back-pointer on a hub, actual backend and its index in + * `hub->backends` array + */ +struct HubCharBackend { + HubChardev *hub; + CharBackend be; + unsigned int be_ind; +}; + +struct HubChardev { + Chardev parent; + /* Linked backends */ + HubCharBackend backends[MAX_HUB]; + /* + * Number of backends attached to this hub. Once attached, a + * backend can't be detached, so the counter is only increasing. + * To safely remove a backend, hub has to be removed first. + */ + unsigned int be_cnt; + /* + * Number of CHR_EVEN_OPENED events from all backends. Needed to + * send CHR_EVEN_CLOSED only when counter goes to zero. + */ + unsigned int be_event_opened_cnt; + /* + * Counters of written bytes from a single frontend device + * to multiple backend devices. + */ + unsigned int be_written[MAX_HUB]; + unsigned int be_min_written; + /* + * Index of a backend device which got EAGAIN on last write, + * -1 is invalid index. + */ + int be_eagain_ind; +}; +typedef struct HubChardev HubChardev; DECLARE_INSTANCE_CHECKER(MuxChardev, MUX_CHARDEV, TYPE_CHARDEV_MUX) -#define CHARDEV_IS_MUX(chr) \ +DECLARE_INSTANCE_CHECKER(HubChardev, HUB_CHARDEV, + TYPE_CHARDEV_HUB) + +#define CHARDEV_IS_MUX(chr) \ object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_MUX) +#define CHARDEV_IS_HUB(chr) \ + object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_HUB) bool mux_chr_attach_frontend(MuxChardev *d, CharBackend *b, unsigned int *tag, Error **errp); diff --git a/include/chardev/char.h b/include/chardev/char.h index 01df55f9e8..429852f8d9 100644 --- a/include/chardev/char.h +++ b/include/chardev/char.h @@ -232,6 +232,7 @@ OBJECT_DECLARE_TYPE(Chardev, ChardevClass, CHARDEV) #define TYPE_CHARDEV_NULL "chardev-null" #define TYPE_CHARDEV_MUX "chardev-mux" +#define TYPE_CHARDEV_HUB "chardev-hub" #define TYPE_CHARDEV_RINGBUF "chardev-ringbuf" #define TYPE_CHARDEV_PTY "chardev-pty" #define TYPE_CHARDEV_CONSOLE "chardev-console" diff --git a/chardev/char-hub.c b/chardev/char-hub.c new file mode 100644 index 0000000000..3a4aae3289 --- /dev/null +++ b/chardev/char-hub.c @@ -0,0 +1,301 @@ +/* + * QEMU Character Hub Device + * + * Author: Roman Penyaev + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "qemu/option.h" +#include "chardev/char.h" +#include "chardev-internal.h" + +/* + * Character hub device aggregates input from multiple backend devices + * and forwards it to a single frontend device. Additionally, hub + * device takes the output from the frontend device and sends it back + * to all the connected backend devices. + */ + +/* + * Write to all backends. Different backend devices accept data with + * various rate, so it is quite possible that one device returns less, + * then others. In this case we return minimum to the caller, + * expecting caller will repeat operation soon. When repeat happens + * send to the devices which consume data faster must be avoided + * for obvious reasons not to send data, which was already sent. + * Called with chr_write_lock held. + */ +static int hub_chr_write(Chardev *chr, const uint8_t *buf, int len) +{ + HubChardev *d = HUB_CHARDEV(chr); + int r, i, ret = len; + unsigned int written; + + /* Invalidate index on every write */ + d->be_eagain_ind = -1; + + for (i = 0; i < d->be_cnt; i++) { + if (!d->backends[i].be.chr->be_open) { + /* Skip closed backend */ + continue; + } + written = d->be_written[i] - d->be_min_written; + if (written) { + /* Written in the previous call so take into account */ + ret = MIN(written, ret); + continue; + } + r = qemu_chr_fe_write(&d->backends[i].be, buf, len); + if (r < 0) { + if (errno == EAGAIN) { + /* Set index and expect to be called soon on watch wake up */ + d->be_eagain_ind = i; + } + return r; + } + d->be_written[i] += r; + ret = MIN(r, ret); + } + d->be_min_written += ret; + + + return ret; +} + +static int hub_chr_can_read(void *opaque) +{ + HubCharBackend *backend = opaque; + CharBackend *fe = backend->hub->parent.be; + + if (fe && fe->chr_can_read) { + return fe->chr_can_read(fe->opaque); + } + + return 0; +} + +static void hub_chr_read(void *opaque, const uint8_t *buf, int size) +{ + HubCharBackend *backend = opaque; + CharBackend *fe = backend->hub->parent.be; + + if (fe && fe->chr_read) { + fe->chr_read(fe->opaque, buf, size); + } +} + +static void hub_chr_event(void *opaque, QEMUChrEvent event) +{ + HubCharBackend *backend = opaque; + HubChardev *d = backend->hub; + CharBackend *fe = d->parent.be; + + if (event == CHR_EVENT_OPENED) { + /* + * Catch up with what was already written while this backend + * was closed + */ + d->be_written[backend->be_ind] = d->be_min_written; + + if (d->be_event_opened_cnt++) { + /* Ignore subsequent open events from other backends */ + return; + } + } else if (event == CHR_EVENT_CLOSED) { + if (!d->be_event_opened_cnt) { + /* Don't go below zero. Probably assert is better */ + return; + } + if (--d->be_event_opened_cnt) { + /* Serve only the last one close event */ + return; + } + } + + if (fe && fe->chr_event) { + fe->chr_event(fe->opaque, event); + } +} + +static GSource *hub_chr_add_watch(Chardev *s, GIOCondition cond) +{ + HubChardev *d = HUB_CHARDEV(s); + Chardev *chr; + ChardevClass *cc; + + if (d->be_eagain_ind == -1) { + return NULL; + } + + assert(d->be_eagain_ind < d->be_cnt); + chr = qemu_chr_fe_get_driver(&d->backends[d->be_eagain_ind].be); + cc = CHARDEV_GET_CLASS(chr); + if (!cc->chr_add_watch) { + return NULL; + } + + return cc->chr_add_watch(chr, cond); +} + +static bool hub_chr_attach_chardev(HubChardev *d, Chardev *chr, + Error **errp) +{ + bool ret; + + if (d->be_cnt >= MAX_HUB) { + error_setg(errp, "hub: too many uses of chardevs '%s'" + " (maximum is " stringify(MAX_HUB) ")", + d->parent.label); + return false; + } + ret = qemu_chr_fe_init(&d->backends[d->be_cnt].be, chr, errp); + if (ret) { + d->backends[d->be_cnt].hub = d; + d->backends[d->be_cnt].be_ind = d->be_cnt; + d->be_cnt += 1; + } + + return ret; +} + +static void char_hub_finalize(Object *obj) +{ + HubChardev *d = HUB_CHARDEV(obj); + int i; + + for (i = 0; i < d->be_cnt; i++) { + qemu_chr_fe_deinit(&d->backends[i].be, false); + } +} + +static void hub_chr_update_read_handlers(Chardev *chr) +{ + HubChardev *d = HUB_CHARDEV(chr); + int i; + + for (i = 0; i < d->be_cnt; i++) { + qemu_chr_fe_set_handlers_full(&d->backends[i].be, + hub_chr_can_read, + hub_chr_read, + hub_chr_event, + NULL, + &d->backends[i], + chr->gcontext, true, false); + } +} + +static void qemu_chr_open_hub(Chardev *chr, + ChardevBackend *backend, + bool *be_opened, + Error **errp) +{ + ChardevHub *hub = backend->u.hub.data; + HubChardev *d = HUB_CHARDEV(chr); + strList *list = hub->chardevs; + + d->be_eagain_ind = -1; + + if (list == NULL) { + error_setg(errp, "hub: 'chardevs' list is not defined"); + return; + } + + while (list) { + Chardev *s; + + s = qemu_chr_find(list->value); + if (s == NULL) { + error_setg(errp, "hub: chardev can't be found by id '%s'", + list->value); + return; + } + if (CHARDEV_IS_HUB(s) || CHARDEV_IS_MUX(s)) { + error_setg(errp, "hub: multiplexers and hub devices can't be " + "stacked, check chardev '%s', chardev should not " + "be a hub device or have 'mux=on' enabled", + list->value); + return; + } + if (!hub_chr_attach_chardev(d, s, errp)) { + return; + } + list = list->next; + } + + /* Closed until an explicit event from backend */ + *be_opened = false; +} + +static void qemu_chr_parse_hub(QemuOpts *opts, ChardevBackend *backend, + Error **errp) +{ + ChardevHub *hub; + strList **tail; + int i; + + backend->type = CHARDEV_BACKEND_KIND_HUB; + hub = backend->u.hub.data = g_new0(ChardevHub, 1); + qemu_chr_parse_common(opts, qapi_ChardevHub_base(hub)); + + tail = &hub->chardevs; + + for (i = 0; i < MAX_HUB; i++) { + char optbuf[16]; + const char *dev; + + snprintf(optbuf, sizeof(optbuf), "chardevs.%u", i); + dev = qemu_opt_get(opts, optbuf); + if (!dev) { + break; + } + + QAPI_LIST_APPEND(tail, g_strdup(dev)); + } +} + +static void char_hub_class_init(ObjectClass *oc, void *data) +{ + ChardevClass *cc = CHARDEV_CLASS(oc); + + cc->parse = qemu_chr_parse_hub; + cc->open = qemu_chr_open_hub; + cc->chr_write = hub_chr_write; + cc->chr_add_watch = hub_chr_add_watch; + /* We handle events from backends only */ + cc->chr_be_event = NULL; + cc->chr_update_read_handler = hub_chr_update_read_handlers; +} + +static const TypeInfo char_hub_type_info = { + .name = TYPE_CHARDEV_HUB, + .parent = TYPE_CHARDEV, + .class_init = char_hub_class_init, + .instance_size = sizeof(HubChardev), + .instance_finalize = char_hub_finalize, +}; + +static void register_types(void) +{ + type_register_static(&char_hub_type_info); +} + +type_init(register_types); diff --git a/chardev/char.c b/chardev/char.c index 7705da5ad0..5a9e9762ad 100644 --- a/chardev/char.c +++ b/chardev/char.c @@ -943,7 +943,26 @@ QemuOptsList qemu_chardev_opts = { },{ .name = "chardev", .type = QEMU_OPT_STRING, + }, + /* + * Multiplexer options. Follows QAPI array syntax. + * See MAX_HUB macro to obtain array capacity. + */ + { + .name = "chardevs.0", + .type = QEMU_OPT_STRING, + },{ + .name = "chardevs.1", + .type = QEMU_OPT_STRING, },{ + .name = "chardevs.2", + .type = QEMU_OPT_STRING, + },{ + .name = "chardevs.3", + .type = QEMU_OPT_STRING, + }, + + { .name = "append", .type = QEMU_OPT_BOOL, },{ @@ -1106,8 +1125,8 @@ ChardevReturn *qmp_chardev_change(const char *id, ChardevBackend *backend, return NULL; } - if (CHARDEV_IS_MUX(chr)) { - error_setg(errp, "Mux device hotswap not supported yet"); + if (CHARDEV_IS_MUX(chr) || CHARDEV_IS_HUB(chr)) { + error_setg(errp, "For mux or hub device hotswap is not supported yet"); return NULL; } diff --git a/chardev/meson.build b/chardev/meson.build index 70070a8279..56ee39ac0b 100644 --- a/chardev/meson.build +++ b/chardev/meson.build @@ -3,6 +3,7 @@ chardev_ss.add(files( 'char-file.c', 'char-io.c', 'char-mux.c', + 'char-hub.c', 'char-null.c', 'char-pipe.c', 'char-ringbuf.c',